This invention relates to electromagnetic projectile launchers and more particularly to such launchers employing magnetic fields for spin stabilization of projectiles.
Electromagnetic projectile launchers are known which comprise a pair of conductive rails, a sliding conductive armature between the rails, a source of high current, and means for commutating this current into the rails and into the armature. This places an electromagnetic force on the armature which propels it along the conductive rails.
Present electromagnetic launchers are configured with parallel-sided rails and while this does have advantages in some cases, it essentially precludes imparting rotation to a projectile for spin stabilization. Therefore parallel-sided rail launchers utilize alternate stabilization means such as fins attached to the projectile. Electromagnetic launchers have been proposed that have skewed conductive rails to cause spin stabilization of the projectile where the pushing armature sabot was made to lockstep with the rails by use of notched armatures fitted between multiple rails of the launcher. While multiple skewed rails will impart spin, they have a reduction in force inversely proportional to the number of rails and they introduce additional sliding surface friction resulting in a net reduction in accelerating force for a given amount of available accelerating current. In addition, slotted coaxial elecromagnetic launchers have been proposed which eliminate the reduction in force for a given current but appear to introduce manufacturing complexities and, as with the skewed conductor launcher, require the attachment of the projectile to the armature sabot.
Electromagnetic launchers constructed in accordance with the present invention retain the basic simplicity of the parallel-sided rail launcher by introducing the spin stabilization of a projectile in a muzzle section having a magnetic flux field. To accomplish magnetic spin stabilization of the projectile, the bore of the launcher is made round to accommodate a round projectile as needed for spin stabilization. A launcher in accordance with this invention includes a pair of arcuate conductive rails which are brought together to form a cylindrical bore between the rails, a source of high current, means for commutating the current to the rails, means for conducting the current between the rails and for propelling a cylindrical projectile along the bore, means for generating a magnetic flux field through which the projectile passes during a launch, and means for imparting spin to the projectile in response to the passing of the projectile through the magnetic field.